RNA Polymerase (RNAP) is a powerful biomolecular machine whose motion along DNA can be controlled in an information-dependent manner with nanometer scale precision. As RNAP copies the information in the DNA template to RNA it translocates along the DNA, exerting a linear force of 15-20 pN (1). This forward motion is dependent on the presence of the next incoming ribonucleotide triphosphate (NTP), which is encoded by the DNA template strand sequence. Withholding the required NTP results in the formation of a stable halted elongation complex in which the enzyme remains statically bound to the DNA template until transcription is resumed by addition of substrate (2). Immobilizing RNAP to a solid surface, such as Ni2+-agarose beads, confers the ability to limit the mixture of substrates for each polymerization step, which can be as small as 1 base-pair or 0.34nm (3). In this manner, RNAP can be incrementally 'walked' or positioned along DNA with nanometer scale precision.
Here we utilize modified versions of bacteriophage T7 RNAP, which contain ligand-binding motifs fused to the amino-terminus of the enzyme, in order to facilitate controlled movement and positioning of biomolecules and nanodevices (3-6). Self-assembly of novel DNA nanodevices driven by modified T7 RNAP are demonstrated by atomic force microscopy (AFM) (7).
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William T. McAllister
Microbilogy and Immunology Department
SUNY Health Science Center at Brooklyn
450 Clarkson Ave.
Brooklyn, NY 11203-2098 USA
Phone: 718-270-2109 Fax: 718-270-2565